The aim of this project is to develop phosphorus nuclear magnetic resonance (31P NMR) to the study of phosphate containing metabolites in perfused beating heart. A powerful, new spectrometer especially designed and built for biological studies now has the necessary sensitivity to observe a variety of metabolic intermediates in intact tissue preparation. By synchronising the data acquisition with different intervals of the contraction-relaxation cycle of the heart, fluctuations in the associated biochemical events will be followed. This will aid our understanding of the bioenergetic requirements of the heart. Under conditions of low oxygen supply (hypoxia or anoxia) 31P NMR will be applied to measure quantitatively the volume of the anoxic regions compared to the normoxic ones, thus providing a detailed insight into the events during heart-infarct. This work will be fully integrated with complementary studies using fluorescence and biochemical techniques (being carried out in Philadelphia). In addtion 31P NMR will provide novel information about the state of the intracellular metabolites and will be used to measure the rate at which such molecules diffuse in the tissue. The application of this powerful technique will thus help in the search to understand the conditions of the normal and diseased heart.